[CGP] add another bailout for degenerate code (PR41064)
This is almost the same as:
rL355345
...and should prevent any potential crashing from examples like:
https://bugs.llvm.org/show_bug.cgi?id=41064
...although the bug was masked by:
rL355823
...and I'm not sure how to repro the problem after that change.
llvm-svn: 356218
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index e70e4ee..e8498eb 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1267,8 +1267,12 @@
static bool combineToUSubWithOverflow(CmpInst *Cmp, const TargetLowering &TLI,
const DataLayout &DL, DominatorTree &DT,
bool &ModifiedDT) {
- // Convert (A u> B) to (A u< B) to simplify pattern matching.
+ // We are not expecting non-canonical/degenerate code. Just bail out.
Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
+ if (isa<Constant>(A) && isa<Constant>(B))
+ return false;
+
+ // Convert (A u> B) to (A u< B) to simplify pattern matching.
ICmpInst::Predicate Pred = Cmp->getPredicate();
if (Pred == ICmpInst::ICMP_UGT) {
std::swap(A, B);